BEHAVIORAL ECOLOGY OF JUVENILE PALILA (Loxioides bailleui): FORAGING DEVELOPMENT, SOCIAL DYNAMICS, AND HELPING BEHAVIOR

Abstract

The purpose of this study was to systematically document helping development of foraging in juvenile Palila, an endangered Hawaiian honeycreeper found only on Mauna Kea on the island of Hawaii. Though incidental observations of helpers-at-the-nest have been made, intensive nest monitoring revealed that 30 to 50% of nests had one extra after-second-year male provisioning food to the nestling(s). Helping at the fledgling stage was also confirmed. Radiotracking revealed information regarding foraging development and movement patterns of juveniles. Adult males provided one-on-one food supplementation and foraging instruction to young for three to four months after fledging. Particular benchmarks in the development of foraging skills in juveniles were identified. Juvenile survival may be a factor limiting the Palila population. This investigation constitutes the first detailed study of a juvenile Hawaiian forest bird, and thus, may serve as model for understanding the ecology of other species.